Homemade copper conductive paint / ink

Heres an interesting method for making a home made copper based conductive ink for forming circuits on paper, plastic substrates that is pretty easy and inexpensive and has fairly good chareristics - well when it comes to home made inks it does! - that you can try. Sorry about that its a poor microphone - its integral to the camera and not very good! Anyway, you need ascorbic acid (vitamin C) - 5g, Copper Sulphate - 1g and water at 70C - approx 200mL to make the solutions and a few drops of gum arabic to make the paint (this is sold as watercolour medium by art shops)